Marilyn is a minor character seen on the Grim Adventures of Billy & Mandy episode entitled Billy Idiot. She is voiced by Jennifer Hale.
Marilyn's personality is largely unknown. What is known, is that Marilyn speaks with a lisp and salivates when she talks in what appears to be a frozen or stuck in place crooked smile.
Whether or not, Mrs. Pollywinkle caused her fear and she's just too scared to say anything to the contrary or her behavior is a result of her soul being stolen is unknown.
To date, it's unknown if Marilyn appears in any episodes other than Billy Idiot.
- "Hello..., Hi! I am Marilyn, I like this school so much"
- — Marilyn
Marilyn simply repeats the line over and over again when talking the main trio in this episode, except for when the trio leave, she reveals they will all be stuck in the school forever.